Bleeding brake lines on gm with ABS

Because I asked them for bleeding ONLY and I let them know that I bring the brand new fluid bottle in my car.

Everyone know that CA is so expensive for everything. Yes, you can find $30-$50 anywhere at IL and IA for bleeding only.

IL/IA's most shop are around $40 labor per hour. Cheap?

$40? Sounds cheapest labor price. Sadly, I do not like to live in harsh cold weather... Sorry...
 
Ah Thanks for a sharing, I don't plan buy TECH II anything because it's oudated and not works for most newer cars like OnStar and reprogrammer, So GM MDI is better and afford. I tried Tech II and GM MDI before. I love GM MDI more than Tech II.


I found it from AESwave.com that you trust it.

AESwave.com Store, lab scopes, scan tools, accessories and training for automotive diagnostic equipment!




It's true.

Never buy outdate hardware because they are overprice and slow.

Yes, correct
 
I recall the some Asian vehicles like Subaru or Isuzu if you bleed without scan tool, you must leave the vehicle on the ground. If the vehicle is about to lifting and remove the wheels for bleeding procedure, you have problem with no bleeds, unless you disconnect the linkage from the rear suspension's level control valve (looks like proprication valve). Weird design but I think they are for AWD and brake safety reason?? :dunno:

One time, I bring Subaru to college (I use brake emergency as brake) when I was student that time. Two instructors tried that and no luck and they told me same thing that it need scan tool which they dont have one. So I bring it to shop then solve a problem. I said what's happen? Tech said just use scan tool.
 
$40? Sounds cheapest labor price. Sadly, I do not like to live in harsh cold weather... Sorry...

That's why I don't work for auto technician anymore. I noticed that Diesel technician almost two times more than auto technician for hourly. Sad?

Believe me. I always hate to live in Midwest all in my life. My dream is Southwest. Don't be sorry.
 
Hey, Radioman, You can do manual bleed the brakes without any scan tools, you don't need $4K scan tool.
Did you see the black caps on the ABS box, black caps like plastic covers, pry it with a driverscrew, see the small plunger in the combination valve, you need to push the plunger in that will bypass the brake fluid into the rear brake for bleed but you need clamp tool to hold the plunger or have your friend help to hold the plunger while you bleed the brakes. But the plunger is very hard to press in. The special clamp will help. I fabbed my homemade clamps, only used them one time.
 
That's why I don't work for auto technician anymore. I noticed that Diesel technician almost two times more than auto technician for hourly. Sad?

Believe me. I always hate to live in Midwest all in my life. My dream is Southwest. Don't be sorry.

Southwest? Where? My guess... you like Calif...:giggle:
 
I found special tool in etoolcart.com and toolsource.com. The tool name is OTC Proportioning Valve Depressor for ABS Brake System-J-39177. You can see the pic there. Maybe you try to create something to depress the plunger valve (metering rod) with large nylon ties or find way to fab your own tool. I've seen some gifted mechanics like mine, do that with homemade tools or simple mechanic's wire/nylon ties to wrapping the ends of the plungers (combination valve metering rod)
With high end scan tool, you don't need a special tool.
 
I've just skimmed over this thread so forgive me if I've missed something here.

I don't know the exact year of the vehicle, but if the car is computer controlled I wonder if the ABS is controlled by computer. As I understand it, ABS works on pressure and there must be a sensor for it. I'm guessing they might not need to be bled the same as non-anti lock breaks?

If you are having that much of a hard time bleeding the breaks, it's probably either something defective or you have too much air in the system. Just my guess..
 
I've just skimmed over this thread so forgive me if I've missed something here.

I don't know the exact year of the vehicle, but if the car is computer controlled I wonder if the ABS is controlled by computer. As I understand it, ABS works on pressure and there must be a sensor for it. I'm guessing they might not need to be bled the same as non-anti lock breaks?

If you are having that much of a hard time bleeding the breaks, it's probably either something defective or you have too much air in the system. Just my guess..

Yes, you are correct but the ABS systems use 3 or 4 wheel sensors , Not one sensor because the ABS computer read the AC voltage signals from the wheel sensors to matching the same wheel speeds. If one wheel is about lock-up in panic brake then ABS computer will pump out the hydraulic (brake fluid) to other non- lockup wheels to control the brake in even balance to prevent skip. One other thing with the wheel sensors, if the tire is about under-inflate or flat that means un-even wheel speeds, the computer will flag and set ABS codes or turn ABS light on or "Tire monitor" light will turn on to remind you to check the tire air pressure.
If you drive in slow speed and notice the ABS light pop up without hit brake pedal that means you have problem with wheel sensors (cause corroded sensors or open circuit or flat tires). Yes, they are a real pain in the ass for diagnostic time/bleeding procedures. That is ABS system design for....
 
Yes, you are correct but the ABS systems use 3 or 4 wheel sensors , Not one sensor because the ABS computer read the AC voltage signals from the wheel sensors to matching the same wheel speeds. If one wheel is about lock-up in panic brake then ABS computer will pump out the hydraulic (brake fluid) to other non- lockup wheels to control the brake in even balance to prevent skip. One other thing with the wheel sensors, if the tire is about under-inflate or flat that means un-even wheel speeds, the computer will flag and set ABS codes or turn ABS light on or "Tire monitor" light will turn on to remind you to check the tire air pressure.
If you drive in slow speed and notice the ABS light pop up without hit brake pedal that means you have problem with wheel sensors (cause corroded sensors or open circuit or flat tires). Yes, they are a real pain in the ass for diagnostic time/bleeding procedures. That is ABS system design for....

Forgive me if I am speaking in ancient terms, but is there a sensor on the master cylinder? Perhaps the breaks bleed only from there?

There is no reason you can't bleed a line unless something is trapping the air, right? Like a valve you cannot open?
 
I don't have the answer on how to bleed with that GM ABS system, but yes there is sensor, where? If it is 2 wheel then there is two sensors and it is locate near the wheel. I forgot what it is called, that has magnetic field with wheel that looks like a gear but it is not. Intended to sense 0 and 1 when the wheel rotates, it sends out continue 0 and 1 which tells the ABS module that the wheel is rotating. In the event of brake being locked, it will stay either 0 or 1 while other wheel continue to send 0 and 1 continue ABS module would pump the brake fluid at the wheel where it continue either 0 or 1. For 4 wheel, it got 4 sensors, one at each wheel.

Damn I forgot what it called, and I had to fix the other day with stupid S-10 that got stuck. Found out that the magnetic sensor and the gear like teeth got no tolerance between. There should be limited tolerance (Hair thin) tolerance between the magnetic sensor and the gear like wheel. GM mechanic couldn't find the problem where I found on my own with help of my friend that knows this stuff.

Found it, I solved the problem because there was no air gap so I just pry it a bit, not much to create air gap and it worked.

To better understand how ABS sensor works. Here is the link

http://www.brakeandfrontend.com/Article/46336/diagnosing_wheel_speed_sensors.aspx


Forgive me if I am speaking in ancient terms, but is there a sensor on the master cylinder? Perhaps the breaks bleed only from there?

There is no reason you can't bleed a line unless something is trapping the air, right? Like a valve you cannot open?
 
Yes, you are correct but the ABS systems use 3 or 4 wheel sensors , Not one sensor because the ABS computer read the AC voltage signals from the wheel sensors to matching the same wheel speeds. If one wheel is about lock-up in panic brake then ABS computer will pump out the hydraulic (brake fluid) to other non- lockup wheels to control the brake in even balance to prevent skip. One other thing with the wheel sensors, if the tire is about under-inflate or flat that means un-even wheel speeds, the computer will flag and set ABS codes or turn ABS light on or "Tire monitor" light will turn on to remind you to check the tire air pressure.
If you drive in slow speed and notice the ABS light pop up without hit brake pedal that means you have problem with wheel sensors (cause corroded sensors or open circuit or flat tires). Yes, they are a real pain in the ass for diagnostic time/bleeding procedures. That is ABS system design for....

How about ESC/ESP?

The NHTSA requires all passenger vehicles to be equipped with ESC by 2012.

The ESC is better than ABS. The ABS system is almost outdated anything.
 
I don't have the answer on how to bleed with that GM ABS system, but yes there is sensor, where? If it is 2 wheel then there is two sensors and it is locate near the wheel. I forgot what it is called, that has magnetic field with wheel that looks like a gear but it is not. Intended to sense 0 and 1 when the wheel rotates, it sends out continue 0 and 1 which tells the ABS module that the wheel is rotating. In the event of brake being locked, it will stay either 0 or 1 while other wheel continue to send 0 and 1 continue ABS module would pump the brake fluid at the wheel where it continue either 0 or 1. For 4 wheel, it got 4 sensors, one at each wheel.



No,AC voltage signals does not sense 0 and 1. You must confused with digital signals.


You should read the link that you post here.

The wheel speed sensors on most vehicles are magnetic and generate an alternating current (AC) signal that increases in frequency and amplitude with wheel speed

Just use DMM and set to AC then connect to ABS's sensors and move wheel then you will see 0.1 VAC to 9 VAC depend on the speed and depend on the brand. It was not hard to do it.

Or use scope lab and make sure ABS's teeth (I forget what it calls) are okay.
 
update - still working on it. I took master cylindeer off and bench bled it. it doesnt seem to quirt fluid evenly from both ports.

If anyone still following this thread- its a 1998 blazer. I finally looked at module and its a kelsey hayes abs unit. According to other forums, they ALLLL have same issues. bleeding . sigh.

deafmodtech- where does that tool go to open the valves? it looks easy enuff to make.

For those who are wondering - I cant exactly take it on the road and try to activate the abs by slamming on brakes since the muffler was taken off and I tried to match it up at local auto parts store so I can weld on a flange for it by reusing the old flange, but they dont have anything in stock. I found one on ebay with welded on flange for same price as generic muffler . should be here in a week or so.
 
Forgive me if I am speaking in ancient terms, but is there a sensor on the master cylinder? Perhaps the breaks bleed only from there?

There is no reason you can't bleed a line unless something is trapping the air, right? Like a valve you cannot open?

Yes, the sensor (actual switch) on the ancient M/C with one port that feed the fluid to the front and rear. If any leak or worn out pads or shoes,then the M/C will lost hydraulic pressure because the plunger inside the bore of M/C, push toward the switch that ground the voltage and trigger the Brake Warning light on. My old Nova has one but I changed the front/rear disc brakes and 2 port M/C with power brake booster and adjustable proportioning valve. More safe than an ancient one port M/C. Single port M/C is very easy to bleeding. I think the brake bleeding sequence for single port M/C is starting with LF, RL, RR, LR but depend on where the hydraulic line is routing. I can't recall.
 
update - still working on it. I took master cylindeer off and bench bled it. it doesnt seem to quirt fluid evenly from both ports.

If anyone still following this thread- its a 1998 blazer. I finally looked at module and its a kelsey hayes abs unit. According to other forums, they ALLLL have same issues. bleeding . sigh.

deafmodtech- where does that tool go to open the valves? it looks easy enuff to make.

For those who are wondering - I cant exactly take it on the road and try to activate the abs by slamming on brakes since the muffler was taken off and I tried to match it up at local auto parts store so I can weld on a flange for it by reusing the old flange, but they dont have anything in stock. I found one on ebay with welded on flange for same price as generic muffler . should be here in a week or so.

Did you use 2 tubes like clear tubes or black vacuum hoses to attaching the ports (use nipple to male threaded adapters) while bleeding on the bench test? Did you rout the tubes from the ports to the bowl (reservoir)? The ends of the tubes must submerge in the fluid (inside the bowl) to prevent the air draw back as you can see bubbles while slowly bleeding. The fluid in bowl should be full while stroke the M/C. If bubbles disappear then plug the ends with penicls, remove from the vise and reinstall in the car and remove one adapter from port and quick install line to the port, finger tight it, do again in other adapter. Lightly tight flare nuts check fluid again, , make sure its full before you pump the pedal. Pump very slowly and depress, wait about 10 seconds, do again in few strokes. Tight front flare nut, leave loose rear flare nut, do pump again in few strokes. Last stroke press pedal you or have someone to hold the pedal down the floor then tight the rear flare nut and release pedal, loose the front flare nut, do repeat...

the proportioning valves are located at the sides of the ABS box, just below of the 3 metal hydraulic tubes (count 3 flare nuts) I think. If you see black cap on the side then pry it with small driverscrew, there you go
 
No,AC voltage signals does not sense 0 and 1. You must confused with digital signals.


You should read the link that you post here.



Just use DMM and set to AC then connect to ABS's sensors and move wheel then you will see 0.1 VAC to 9 VAC depend on the speed and depend on the brand. It was not hard to do it.

Or use scope lab and make sure ABS's teeth (I forget what it calls) are okay.

Actually, on a very basic level, 1 and 0 represent charge or no charge I believe, but I could be wrong. On storage, yes, numeric value is used.
 
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